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Importation and quarantine of Microctonus hyperodae, a South American parasitoid of Argentine stem weevil

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© 1990 New Zealand Plant Protection Society (Inc.) www.nzpps.org Refer to http://www.nzpps.org/terms_of_use.html
© 1990 New Zealand Plant Protection Society (Inc.) www.nzpps.org Refer to http://www.nzpps.org/terms_of_use.html
© 1990 New Zealand Plant Protection Society (Inc.) www.nzpps.org Refer to http://www.nzpps.org/terms_of_use.html
© 1990 New Zealand Plant Protection Society (Inc.) www.nzpps.org Refer to http://www.nzpps.org/terms_of_use.html
© 1990 New Zealand Plant Protection Society (Inc.) www.nzpps.org Refer to http://www.nzpps.org/terms_of_use.html
... Alternatively, collections may have missed the peak level of parasitism of Irish S. lepidus. In the classical biological control programme targeting L. bonariensis, low levels of parasitism (0.7-5.4%) were recorded for M. hyperodae reared in New Zealand quarantine from L. bonariensis collected in South America ( Goldson et al. 1990a), although higher rates of parasitism were recorded in earlier surveys (Loan & Lloyd 1974;Goldson et al. 1990a). Despite this, the parasitoid is an effective biological control agent in the New Zealand agricultural environment where it has been shown to effect significant reductions in adult L. bonariensis populations ( Goldson et al. 1998). ...
... Alternatively, collections may have missed the peak level of parasitism of Irish S. lepidus. In the classical biological control programme targeting L. bonariensis, low levels of parasitism (0.7-5.4%) were recorded for M. hyperodae reared in New Zealand quarantine from L. bonariensis collected in South America ( Goldson et al. 1990a), although higher rates of parasitism were recorded in earlier surveys (Loan & Lloyd 1974;Goldson et al. 1990a). Despite this, the parasitoid is an effective biological control agent in the New Zealand agricultural environment where it has been shown to effect significant reductions in adult L. bonariensis populations ( Goldson et al. 1998). ...
... Of the 787 parasitoid introductions in their data set, none were successful unless there was at least 32% maximum parasitism observed in the pest's native range. Levels of parasitism of 80% and >60% were recorded for Moroccan M. aethiopoides and South American M. hyperodae, respectively, in their native ranges (Aeschlimann 1978;Goldson et al. 1990a). In contrast, a maximum of 7% parasitism was found in S. lepidus in Ireland. ...
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The biological control programme against Sitona lepidus (Gyllenhal) (Coleoptera Braconidae) commenced in 1998 with the first parasitised weevils imported into New Zealand quarantine in 2000 Extensive collections in Europe confirmed that the solitary endoparasitoid Microctonus aethiopoides Loan (Hymenoptera Braconidae) was the principal natural enemy of adult S lepidus With one exception all M aethiopoides reared from S lepidus collected in Europe have been arrhenotokous All M aethiopoides collected from Ireland are thelytokous which obviates the risk of hybridisation with an arrhenotokous Moroccan strain already established in New Zealand Levels of parasitism in S lepidus fieldcollected from Ireland were low (lt;8) and overall averaged 07 Rates of parasitism of S lepidus in New Zealand quarantine have averaged 25 but ranged from 0 to 95 Aspects relating to the rearing and management of Irish M aethiopoides are discussed including possible reasons for low rates of parasitism in quarantine
... In New Zealand, adult ASW populations can reach densities of 700 adults m-2 and cause economic impacts of up to NZ$200M per annum [6][7][8]. Conventional chemical control of ASW is ineffective, environmentally damaging and uneconomical (reviewed in [9,10]), because the stem-mining larvae avoid direct contact with the pesticides [9]. To complement endophyte-based plant resistance [11,12], the solitary wasp Microctonus hyperodae Loan (Hymenoptera: Braconidae) was released for biological control of ASW in 1992. ...
... In New Zealand, adult ASW populations can reach densities of 700 adults m-2 and cause economic impacts of up to NZ$200M per annum [6][7][8]. Conventional chemical control of ASW is ineffective, environmentally damaging and uneconomical (reviewed in [9,10]), because the stem-mining larvae avoid direct contact with the pesticides [9]. To complement endophyte-based plant resistance [11,12], the solitary wasp Microctonus hyperodae Loan (Hymenoptera: Braconidae) was released for biological control of ASW in 1992. ...
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Modified, agricultural landscapes are susceptible to damage by insect pests. Biological control of pests is typically successful once a control agent has established, but this depends on the agent’s capacity to co-evolve with the host. Theoretical studies have shown that different levels of genetic variation between the host and the control agent will lead to rapid evolution of resistance in the host. Although this has been reported in one instance, the underlying genetics have not been studied. To address this, we measured the genetic variation in New Zealand populations of the pasture pest, Argentine stem weevil (Listronotus bonariensis), which is controlled with declining effectiveness by a parasitoid wasp, Microctonus hyperodae. We constructed a draft reference genome of the weevil, collected samples from a geographical survey of 10 sites around New Zealand, and genotyped them using a modified genotyping-by-sequencing approach. New Zealand populations of Argentine stem weevil have high levels of heterozygosity and low population structure, consistent with a large effective population size and frequent gene flow. This implies that Argentine stem weevils were able to evolve more rapidly than their biocontrol agent, which reproduces asexually. These findings show that monitoring genetic diversity in biocontrol agents and their targets is critical for long-term success of biological control.
... The parasitoid M. hyperodae was imported from South America in the early 1990s for biological control of L. bonariensis and was released at various sites throughout New Zealand (Goldson et al., 1990(Goldson et al., , 1993McNeill et al., 2002). Ensuing high parasitism rates of up to 90% in the adults in the common L. perenne pastures (Barker and Addison, 2006) were subsequently shown to have had an appreciable impact on the weevil populations (Barker, 2013). ...
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New Zealand pastures largely comprising Lolium ryegrass species (Poales: Poaceae) are worth $19.6B and are subject to major pest impacts. A very severe pest is the Argentine stem weevil Listronotus bonariensis (Kuschel) (Coleoptera: Curculionidae). This has been previously suppressed by the importation biological control agent, Microctonus hyperodae Loan (Hymenoptera: Braconidae). However, this suppression has recently declined and is subject to investigation. It has been hypothesised that grass type influences the parasitism avoidance behaviour by the weevil and thus parasitism rates. This study explored the hypothesis using three common pasture grasses: a diploid Lolium perenne x Lolium multiflorum hybrid ryegrass (cv. Manawa), a tetraploid Italian ryegrass L. multiflorum Lam. (cv. Tama), and a diploid perennial ryegrass L. perenne L. (cv. Samson). The described laboratory-based microcosm methodology determined the extent of weevil avoidance behaviour on each of these three grasses when subjected to the parasitoid. Such reaction was gauged by the extent of reduced weevil on-plant presence and feeding compared to the control populations. In the absence of the parasitoid, the hybrid cv. Manawa ryegrass is as highly favoured by the weevil as the tetraploid cv. Tama. On diploid cv. Samson, feeding is considerably less. In the presence of the parasitoid, weevils on the tetraploid cv. Tama plants showed little avoidance activity in response to the parasitoid and it can be argued that the benefits of staying on this plant outweighed the possibility of parasitism. Conversely and surprisingly, in the parasitoid’s presence, weevils on diploid cv. Manawa showed very strong avoidance behaviour leading to levels of exposure similar to those found on the less-preferred diploid cv. Samson. These findings reflect how weevil parasitism rates have declined in most Lolium grasses, particularly diploids, since the 1990s, but not in the tetraploid L. multiflorum. This contribution supports the hypothesis that the decline in weevil parasitism rates has been the result of rapid evolution arising from parasitoid-induced selection pressure and the countervailing effect of the nutritional quality of the host plants.
... However, despite this success there still remained a need for an integrated approach to the management of the weevil. Accordingly, M. hyperodae a parthenogenetic endoparasitoid of L. bonariensis was imported from South America and released at various sites across New Zealand, but particularly in the northern North Island, central South Island and southern South Island (Goldson et al. 1990(Goldson et al. , 1992Ferguson et al. 1997;McNeill et al. 2002). High parasitism rates of up to 90% in the adults (Barker and Addison 2006) were subsequently shown to have had an appreciable impact on the weevil populations (Barker 2013). ...
... Further, HIPVs are known to also act as indirect plant defence mechanisms by attracting predators and parasitoids of the attacking phytophagous insect (Fuchs and Krauss 2019). The parasitic wasp, M. hyperodae, was introduced to New Zealand to control ASW (Goldson et al. 1990) and, although responses to HIPVs have never been assessed, it is conceivable that this wasp could also utilise these chemical cues when searching for weevils to parasitize. The primitive habitat and 'centre-of-origin' of ASW are thought to be in the 'Mallines' of Argentina (Lloyd 1966). ...
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Argentine stem weevil adults (ASW, Listronotus bonariensis ) feed on the leaves of agricultural grasses and their larvae mine the pseudostem, causing extensive damage that can result in plant death. Plants emit volatiles that serve as signals to host-searching insects and these odours can be altered by both herbivory and fungal endophyte-infection. This study investigated whether ASW adults utilise olfaction to identify their host plants, perennial ryegrass ( Lolium perenne ), and if conspecific herbivory or the presence of Epichloë festucae var. lolii fungal endophytes (strain wild-type or AR1) influenced such responses. Results from olfactometer bioassays established that ASW adults were able to utilise their olfactory response to orient towards volatiles released by perennial ryegrass and further, the weevils displayed a preference for plants previously damaged by conspecific weevils. However, there was no evidence that weevils had the ability to distinguish between endophyte-infected and endophyte-free plants using olfaction alone. Using a push–pull extraction technique, thirteen volatile compounds were identified in the blend released by perennial ryegrass. Endophyte and herbivory were found to alter these volatile compounds and quantities emitted by this forage grass. This study suggests that despite observing differences in the plant volatile blend, ASW do not perceive endophyte (wild-type and AR1) using olfaction alone and must rely on other cues, e.g. contact chemoreception or post-ingestional malaise, to detect the presence of a bioactive endophyte in an otherwise acceptable host plant.
... Generally, parasitism by these species was found to occur at low levels in their native ranges. Goldson et al. (1990b) found that the prevailing level of parasitism of L. bonariensis by M. hyperodae in temperate South America was c.5%, although often the sampled weevil populations showed no parasitism at all (S. L. Goldson, unpublished data). ...
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New Zealand's intensive pastures, comprised almost entirely introduced Lolium L. and Trifolium L. species, are arguably the most productive grazing-lands in the world. However, these areas are vulnerable to destructive invasive pest species. Of these, three of the most damaging pests are weevils (Coleoptera: Curculionidae) that have relatively recently been controlled by three different introduced parasitoids, all belonging to the genus Microctonus Wesmael (Hymenoptera: Braconidae). Arguably that these introduced parasitoids have been highly effective is probably because they, like many of the exotic pest species, have benefited from enemy release. Parasitism has been so intense that, very unusually, one of the weevils has now evolved resistance to its parthenogenetic parasitoid. This review argues that New Zealand's high exotic pasture pest burden is attributable to a lack of pasture plant and natural enemy diversity that presents little biotic resistance to invasive species. There is a native natural enemy fauna in New Zealand that has evolved over millions of years of geographical isolation. However, these species remain in their indigenous ecosystems and, therefore, play a minimal role in creating biotic resistance in the country's exotic ecosystems. For clear ecological reasons relating to the nature of New Zealand pastures, importation biological control can work extremely well. Conversely, conservation biological control is less likely to be effective than elsewhere.
... Prestidge et al. 1989), and it is also possible that the weevil can survive on endemic young Deyeuxia spp. (Goldson et al. 1990). Prior to its effective management, ASW was estimated to cause losses to the New Zealand pastoral sector of NZ$78-251M annually (Prestidge et al. 1991), and is therefore the worst pest in New Zealand's pastures. ...
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This contribution examines the potential for error when the results from laboratory-based experiments are extrapolated to inform field ecological analyses. The effects on the reproductivity of different population densities of Argentine stem weevil Listronotus bonariensis (Kuschel) were studied using caged populations of immature (pre-reproductive) and mature (reproductive) adults. Three densities of weevils equivalent to 125/m2 (low), 375/m2 (medium) and 1125/m2 (high) from field-collected pre- and reproductive populations were confined in plastic containers for either 11 or 21 days with ad libitum food and oviposition-site resources. The impact of the medium and high densities on weevil reproductive physiology was assessed by dissection at 11 and 21 days. Data were collected on sexual maturity, wing muscle development, and the presence of eggs and β-carotene crystals. Only very weak treatment effect responses were observed. A significantly higher percentage of immature females showed oöcyte resorption at high densities at 11 days, but by 21 days this had disappeared. Males had significantly less developed testes at high densities at 11 days, but again by 21 days this effect was not significant. Mature females had significantly larger wing muscles at high density after 11 days of caging; however, by 21 days this effect had gone. For both immature and mature females, there was no effect of density on the relationship between eggs per female and wing muscle index. The low density treatment was not included in this analysis due to low weevil numbers surviving at the end of the experiment. It is concluded that caging itself had a far greater effect on the physiology of the weevils than any imposed population density treatments, which is contrary to the findings of field population-dynamics analyses. Care should be taken in extrapolating laboratory trials involving this genus, and indeed it may occur more widely, to explain field situations.
... New Zealand's founding populations of M. hyperodae were collected from eight disparate locations in four South American countries (Goldson et al. 1990). These were Brazil (Porto Alegre), Argentina (Ascasubi, S. C. de Bariloche, and General Roca, Mendoza), Chile (La Serena and Concepcion) and Uruguay (Colonia). ...
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The Argentine stem weevil parasitoid Microctonus hyperodae Loan (Hymenoptera Braconidae) was first released in Hawkes Bay at two locations in 1995 In 2000 eight Hawkes Bay sites situated up to ca 55 km from the original release sites were surveyed to determine the presence of M hyperodae The parasitoid was recovered from all eight sites with the proportion of weevils parasitised at each site ranging from 1 to 44 Although parasitoids originating from east and west of the South American Andes mountains had been introduced to both Hawkes Bay release locations in 1995 genetic markers based on variation in malate dehydrogenase allozymes showed that eastern parasitoids predominated at all of the sites sampled in 2000 with western parasitoids occurring in low numbers at only three sites These results are compared with previous results from other New Zealand locations and their implications discussed
... New Zealand's founding populations of M. hyperodae were collected from eight disparate locations in four South American countries (Goldson et al. 1990). These were Brazil (Porto Alegre), Argentina (Ascasubi, S. C. de Bariloche, and General Roca, Mendoza), Chile (La Serena and Concepcion) and Uruguay (Colonia). ...
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The Argentine stem weevil parasitoid, Microctonus hyperodae Loan (Hymenoptera: Braconidae), was first released in Hawke's Bay at two locations in 1995. In 2000, eight Hawke's Bay sites situated up to ca 55 km from the original release sites were surveyed to determine the presence of M. hyperodae. The parasitoid was recovered from all eight sites, with the proportion of weevils parasitised at each site ranging from 1% to 44%. Although parasitoids originating from east and west of the South American Andes mountains had been introduced to both Hawke's Bay release locations in 1995, genetic markers based on variation in malate dehydrogenase allozymes showed that eastern parasitoids predominated at all of the sites sampled in 2000, with western parasitoids occurring in low numbers at only three sites. These results are compared with previous results from other New Zealand locations and their implications discussed. INTRODUCTION Argentine stem weevil, Listronotus bonariensis (Kuschel) (Coleoptera: Curculionidae), was discovered in New Zealand in 1927 (Marshall 1937) where it has become a well known pest of pasture grasses and other graminaceous crops. In Hawke's Bay, L. bonariensis larvae can severely curtail establishment of sweet corn crops by transferring from pasture remnants to sweet corn seedlings. Estimated plant population loss in one crop in November 2000 was 30% (M. Slay, pers. obs.). Though insecticides can be effective, they are not an option for the increasing number of growers using organic production methods. The South American endoparasitoid Microctonus hyperodae Loan (Hymenoptera: Braconidae) was identified as having potential for biological control of L. bonariensis (Loan & Lloyd 1974) and it has since been established throughout New Zealand (Goldson et al. 1998). It was released at two Hawke's Bay sites in 1995 (McNeill et al. 2002). New Zealand's founding populations of M. hyperodae were collected from eight disparate locations in four South American countries (Goldson et al. 1990). These were Brazil (Porto Alegre), Argentina (Ascasubi, S. C. de Bariloche, and General Roca, Mendoza), Chile (La Serena and Concepcion) and Uruguay (Colonia). Parasitoids from each geographic population were released in equal numbers at each New Zealand location to provide the populations with equal chances of establishing. It was postulated that the South American populations best suited to the conditions encountered at each New Zealand release locality would establish there. The asexual reproduction of M. hyperodae (Loan & Lloyd 1974) has precluded interbreeding between the South American
Article
Two species from the genus Microctonus Wesmael (Hymenoptera: Braconidae) have been introduced into New Zealand as biocontrol agents of pest weevils in pasture. Both parasitoids have similar life cycles and co-exist in pasture along with their respective weevil hosts. However, winter parasitism rates by M. hyperodae Loan are low in comparison to the Irish biotype of M. aethiopoides’ Loan. Population studies at two Waikato sites over three consecutive seasons of parasitoid activity showed that M. aethiopoides recovered from near extinction each spring and built up to effective levels by winter because hosts were available continuously throughout summer and autumn. In contrast, M. hyperodae began each season at higher larval populations and parasitism levels than M. aethiopoides, but populations and parasitism levels declined during late summer and early autumn due to low host availability. The contrast between species is consistent with the high levels of endophyte-conferred pest-resistant grass in the pastures, which impacts strongly on M. hyperodae’s host weevil abundance during summer but has no effect on M. aethiopoides’ host weevils which feed only on clovers. It was accentuated by a warming climate with the now regular occurrence of a third host generation after most M. hyperodae adult activity had ceased.
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